1. Field of the Invention
The present invention relates generally to a process and system for recovering copper from a contaminated copper-bearing source and more particularly to a hydrometallurgical process and system for precipitating copper from a contaminated copper-bearing solution.
2. Brief Description of the Prior Art
The most difficult aspect of recovering copper from a contaminated source such as copper smelter flue dust, refinery waste or other copper-bearing waste streams is the clean-cut separation of the copper from the contaminants in a form suitable for further processing. To date, the predominantly utilized separation techniques have been either the removal of the contaminants from a solution containing both dissolved copper and dissolved contaminants by precipitating the contaminants at high temperatures and pressures or the removal of the copper from the contaminated solution by liquid ion exchange. Each method requires both costly equipment and costly reagents.
Other hydrometallurgical processes have been developed for separating copper from a contaminated source by precipitating the copper from an acidic solution as a sulfide while leaving the contaminants in solution. In one such process, the pH of the solution is adjusted to an initial value of less than 4 and elemental sulfur or cupric sulfide is dispersed into the solution. With the simultaneous introduction of gaseous sulfur dioxide to the solution, the following reactions occur: EQU (1) CuSO.sub.4 +S.degree.+SO.sub.2 +2H.sub.2 O.fwdarw.CuS+2H.sub.2 SO.sub.4 EQU (2) CuSo.sub.4 +CuS+SO.sub.2 +2H.sub.2 O.fwdarw.Cu.sub.2 S+2H.sub.2 SO.sub.4
The precipitated copper sulfides are then separated from the solution and further processed to recover pure copper.